Flame resistant acrylonitrile polymers

ABSTRACT

WHEREIN R1 IS HYDROGEN, CHLORINE, BROMINE OR AN ALKYL RADICAL HAVING FROM 1 TO 9 CARBON ATOMS, R2 IS AN ALKYL RADICAL HAVING 1 TO 22 CARBON ATOMS AND THE SUM OF THE CARBON ATOMS OF R1 AND R2 IS GREATER THAN 9, R3 IS METHYLENE, ISOPROPYLIDENE, OXYGEN OR SULFUR; R4 IS AN ALKYL RADICAL CONTAINING AT LEAST ONE CARBON ATOM; R5 IS A 2,3DIBROMOPROPYL GROUP; X IS BROMINE OR CHLORINE; M IS AN INEGER OF FROM 0 TO 22 AND N IS AN INTEGER OF FROM 0 TO 4 WITH THE PROVISO THAT EACH FORMULA CONTAINS AT LEAST TWO AROMATICALLY BOUND HALOGEN ATOMS.   OR (5) 1-(((X)N-PHENYL)-OOC-(CH2)M-COO-),(X)N-BENZENE   (4) 1-(((X)N,4-(R5-O-)PHENYL)-R3-),(X)N,4-(R5-O-)BENZENE   BENZENE   (3) 1-(((X)N,4-(R4-COO-)PHENYL)-R3-),(X)N,4-(R4-COO-)-   (2) (R1)N,(X)N,(R2-O-)BENZENE   (1) (R1)N,(X)N,(R2-COO-)BENZENE   AN ACRYLONITRILE POLYMER SUCH AS AN ACRYLONITRILE FIBER HAVING IMPROVED FLAME RESISTANCE CONTAINS A HALOGENATED AROMATIC COMPOUND HAVING THE FORMULA

3,66%,35i Patented May 2, 1972 3,660,351 FLAME RESISTANT ACRYLONITRILEPOLYMERS Richard Frederick Schmidt, Stamford, and Joseph Jacinto Pellon,New Canaan, Conn., assignors to American Cyanamid Company, Stamford,Conn. N Drawing. Filed Mar. 12, 1970, Ser. No. 19,124

Int. Cl. C08f 45/58 U.S. Cl. 260-4535 8 Claims ABSTRACT OF THEDISCLOSURE An acrylonitrile polymer such as an acrylonitrile fiberhaving improved flame resistance contains a halogenated aromaticcompound having the formula wherein R is hydrogen, chlorine, bromine oran alkyl radical having from 1 to 9 carbon atoms, R is an alkyl radicalhaving 1 to 22 carbon atoms and the sum of the carbon atoms of R and Ris greater than 9, R is methylene, isopropylidene, oxygen or sulfur; Ris an alkyl radical containing at least one carbon atom; R is a 2,3-dibromopropyl group; X is bromine or chlorine; m is an integer of from 0to 22 and n is an integer of from 0 to 4 with the proviso that eachformula contains at least two aromatically bound halogen atoms.

This invention relates generally to acrylonitrile polymers and moreparticularly to acrylonitrile polymers having improved flame resistance.

Fibers of acrylonitrile polymers are used extensively in various homefurnishings such as carpets, draperies, upholstery and the like. To beentirely acceptable, the home furnishings must be flame resistance orself-extinguishing. While it is relatively easy to provide temporaryflame resistance, it has been found to be very diflicult to providepermanent protection. The more successful processes heretofore proposedhave involved adding halogen bearing aliphatic compounds to the solutionfrom which the fibers are spun. By selecting a hologenated aliphaticcompound which is soluble in organic solvents, it is possible to improveto some extent the flame resistance of fibers spunfrom organic solventsolutions of the polymer. However, it is often preferred to Wet spin theacrylonitrile fiber from a concentrated aqueous saline solution of thepolymer. Experience has shown that when liquid halogenated aliphaticcompounds such as tris (2,3- dibromopropyl) phosphate, halo-aliphaticacid esters,

halogenated parafiines, oils and the like are dispersed in the salinespinning solution, a large amount thereof is lost during spinning andsubsequent dyeing of the fiber. While this loss can be somewhat reducedby using finely divided, solid, high melting halo-aliphatic compoundswhich become entrapped in the fiber matrix, such compounds also tend toreduce the luster of the fiber.

It is, therefore, an object of this invention to provide an improvedflame resistance acrylonitrile polymer. Another object of the inventionis to provide shaped, lustrous and flame resistant acrylonitrilepolymers. Still another object of the invention is to provide shapedacrylonitrile polymers prepared from saline solutions thereof which haveimproved flame resistance. A still further object of the invention is toprovide a process for making flame resistant shaped acrylonitrilepolymers by wet spinning saline solutions of the polymer.

The foregoing objects and others are accomplished in accordance withthis invention, generally speaking, by providing shaped acrylonitrilepolymers containing a halogenated aromatic compound having a meltingpoint below about C. and having one of the formula 1) n 0 (ii R3 whereinR is hydrogen, chlorine, bromine or an alkyl radical having from 1 to 9carbon atoms; R is an alkyl radical having 1 to 22 carbon atoms and thesum of the carbon atoms of R and R is greater than 9; R is methylene,isopropylidene, oxygen or sulfur; R is an alkyl radical containing atleast one carbon atom; R is a 2,3- dibromopropyl group; X is bromine orchlorine; m is an integer of from 0 to 22 and n is an integer of from 0to 4 with the proviso that each formula contains at least twoaromatically bound halogen atoms. R may be, for example, methyl, ethyl,hexyl, nonyl or the like. R and R may be, for example, methyl, ethyl,butyl, octyl, octadecyl or the like. It has been found that a fiber ofan acrylonitrile polymer having improved flame resistance can beproduced without substantial deleterious effect upon the luster thereofby substantially uniformly mixing with a saline solution of the polymerone of the halogenated aromatic compounds of the above formulae, ormixtures thereof, and spinning the resulting mixture into an aqueouscoagulating bath. The halogenated aromatic compounds dispersed in thespinning solution in accordance with this invention are not removed fromthe fiber during spinning or in subsequent dyeing steps in sufficientquantity to eflect significantly the flame resistant properties of 3 thefiber. In fact, more than 90 percent of the halogenated compounddispersed in the spinning solution often remains in the fiber afterspinning and dyeing.

The flame retardant compounds of this invention are liquids or waxeshaving a melting point of less than about 100 C. It is surprising thatalthough such compounds are liquids or low melting waxes and are notsoluble in the spinning dope, they can be heterogeneously dispersed inthe dope and very little if any loss will occur during wet spinning,washing and other processing of the resulting fibers. As indicated bythe formula, the number of halogen atoms will vary from one compound toanother but the total number of aromatically bound chlorine or bromineatoms in the compound should be at least two and preferably at leastthree with not more than five per aromatic ring. Any compound having oneof the formulae set forth above may be used such as, for example,di(2,4,-6- tribromophenyl)adipate, di(2,4,6-tribromophenyl) sebacate,di(4-octanoyl dibromophenyl) propane, 4-nonyl, 2,6-dibromophenylacetate, pentabromophenyl oleate, tribromophenyl stearate,pentabromophenyl stearate, di- (2,4,6-trichlorophenyl) sebacate,di(4-octanoyl dichlorophenyl) propane, trichlorophenyl stearate,di(2,4,6-trichlorophenyl) malonate, di(4 bromopropoxy 2,3,5,6-tetrabromophenyl) propane and the like. It is pointed out that compoundscontaining both aliphatically and aromatically bound halogen atoms canbe used but such a compound must contain at least two aromatically boundhalogen atoms.

The amount of halogenated aromatic compound included in the salinesolution of the acrylonitrile polymer will vary with the percentagehalogen in the compound and to some extent upon the particular halogenpresent. Any amount of brominated or chlorinated aromatic compoundhaving the above formula will improve the flame resistance of anacrylonitrile polymer so all suitable concentrations in the spinningsolution are broadly contemplated. Best results have been obtained sofar with from about 1 percent to about 15 percent bromine or from about2 percent to about 30 percent chlorine, or equivalent mixtures ofbromine and chlorine based on the weight of acrylonitrile fiber in thespinning solution so it is preferred to use an amount within theseranges. With most halogenated aromatic compounds found suitable inaccordance with this invention, the required amount of bromine and/orchlorine is supplied by from about 1 percent to about 20 percent byweight of the halogenated aromatic compound. The halogenated aromaticcompounds may be used alone or in combination with other fiameretardants such as antimony oxide and phosphorus compounds.

In practicing the invention, the halogenated aromatic compound is mixedsufficiently uniformly with a saline spinning solution and the resultingmixture is wet spun by conventional methods. To improve the flameresistance of a fiber spun from a saline solution, a spinning solutioncontaining an acrylonitrile polymer, water and a saline solvent for thepolymer such as sodium thiocyanate, zinc chloride or the like is stirredwith the halogenated aromatic compound in a mixer adapted to impart ashearing action to the mixture until a substantially uniform dispersionof droplets of the halogenated compound in the spinning solution isobtained. The resulting mixture is then spun into an aqueous coagulatingbath, stretched and dyed. The particles or droplets of liquidhalogenated aromatic compound dispersed in the fiber are predominantlyless than about 20 microns in cross-section.

The invention contemplates improving the flame resistance of anyacrylonitrile polymer including those disclosed in U.S. 3,028,371. Theterm acrylonitrile polymer is used herein to mean acrylonitrilehomopolymers and copolymers containing at least about 70 percent byweight acrylonitrile copolymerized with other mono-olefinic compounds ofthe type disclosed in U.S. 3,028,371 and other prior publications.

Although the invention is described herein to a large extent withrespect to the production of fibers having improved flame resistance forconvenience, it is also applicable to the production of other shapedarticles such as tubes, films and the like.

As indicated by the formula of the halogenated aromatic compounds foundadvantageous for improving the flame resistance of acrylonitrilepolymers, the halogen atoms must be aromatically bound and the sum ofthe carbon atoms in R and R of Formulae 1 and 2 must be greater than 9.The halogenated aromatic compounds are more resistant to chemical attackby aqueous saline solutions than halogenated aliphatic compounds. Suchcompounds are also retained to a greater extent by the shapedacrylonitrile polymer than are halogenated aliphatic compounds. Maximumretention is important not only for optimum flame proofing but alsobecause the presence of halogen compounds in the solvent interferes withsolvent recovery and introduces corrosion problems.

Any suitable saline solvent may be used to prepare the spinning solutionsuch as, for example, those disclosed in Rein U.S. 2,140,921 andCresswell 2,558,730. Specific examples of suitable salts are sodiumthiocyanate, zinc chloride and the like. The amount of acrylonitrilepolymer dissolved in the aqueous solvent can vary depending upon thecomposition of the polymer, its molecular weight and the particular saltused. Generally, from about 10 percent to about 20 percent by weight ofthe spinning solution will be polymer although even greater percentagescan be used. The solutions containing more than 20 percent polymer maybe spun into air prior to washing with water to remove the salt. Thespinning solution may contain, in addition to the flame retardant, otheradditives or modifying agents, if desired. Conventional spinningequipment used for making filaments and fibers may be used.

The acrylonitrile polymers provided by this invention can be used toadvantage in making draperies, carpets and other household furnishings.

In the following examples all parts are by weight unless otherwisespecified.

EXAMPLE I About 8 parts of 4-nonyl-2,6-dibromophenyl acetate are mixedwith about 1000 parts of a spinning solution containing about 112 partsof an acrylonitrile copolymer, about 365 parts sodium thiocyanate andabout 523 parts water and the mixture is agitated with a mixer adaptedto impart a shearing action thereto until a substantially uniformdispersion of the bromine substituted compound in the spinning solutionis obtained. The copolymer is about 10.7 percent methyl-methacrylate andabout 89.3 percent acrylonitrile. The resulting mixture is wet spun froma wet-spinning apparatus into a coagulating bath containing about 10percent sodium thiocyanate and about percent water at about 0 C. Aspinnerette of the type disclosed by Cresswell in U.S. 2,558,730 may beused.

The acrylic fiber thus produced contains the 4-nonyl- 2,6-dibromophenylacetate as small particulate inclusions. The fiber is completelylustrous and is self-extinguishing. From about 92 percent to about 96percent or more of the 4-nonyl-2,6-dibromophenyl acetate added to thespinning solution is retained in the coagulated fiber and very little,if any, is lost as the fiber is dyed in water at C. for about one hour.

EXAMPLE II Example I is repeated except about 4.1 percent (based on theweight of copolymer) of di(2,4,6-tribromophenyl) sebacate aresubstituted for the 4-nonyl-2,6-dibromophenyl acetate. About 99 percentof the di(2,4,6-tribromo phenyl) sebacate is retained in the fiber afterspinning and about 92.5 percent thereof is retained after dyeing thefiber.

When about 6 percent di(2,3-dibromopropyl) sebacate are substituted forthe di(2,4,6-tribromophenyl) sebacate,

only about 66.5 percent remains in the fiber after spinning and onlyabout 12.7 percent remains after dyeing.

Substitution of about 4.3 percent tris (2,3-dibromopropyl) phosphate forthe di(2,4,6,-tribromophenyl) sebacate of this Example II results in theproduction of a fiber which retains only 89.5 percent of the phosphateafter spinning and 39 percent after dyeing.

A fiber isobtained which retains only 88 percent of the halogen compoundafter spinning and64 percent after dyeing whenabout 7 percent of abrominated fatty acid ester sold under the trademark Brominex aresubstituted for the di(2,4,6-tribror'nophenyl) sebacate of this ExampleII.

When about 11.8 percent of a chlorinated paraffin sold commercially asHooker C1-40 are substituted for the di(2,4,6-tribro'mophenyl) sebacatethe resulting fiber retains about 86 percent thereof after spinning and73 percent after dyeing. I

EXAMPLE III percent bromine and about 0.25 percent antimony afterdrying. After mock dyeing, the fiber contains about 2.54 percent bromineand about 0.25 percent antimony. The fiber is self-extinguishsing.

Microscopic cross-sectional examination of the fibers produced by eachof the foregoing examples shows that the fire retardant compound ispresent as minute droplets of liquid. Ordinarily, one would expect thisliquid to be easily extracted from the fibers just as it proved to bewith fibers A through C of Example III and those fibers produced byExample II using halogenated compounds not within the scope of thisinvention. However, when those compounds falling within the inventionare used an insignificant amount of the fire retardant is, for somereason not yet explainable, extracted.

Although the invention has been described in detail for the purpose ofillustration, it is to be understood that such detail is solely for thatpurpose and those skilled in the art can make changes therein withoutdeparting from the spirit and scope of the invention except that it islimited by the claims.

What is claimed is:

1. A solid shaped acrylonitrile polymer product pre- TABLE I Numbercarbon Percent Percent retained atoms inbased on Y weight of After AfterFlame retardant R R2 eopolymer spin dyeing A 4-0etyl 2,6-dibr0mophen0l 80 5.7 71.5 54.0 B 4-n0nyl 2,61iibromophenol 9 0 6. 2 79. 5 69. 5 C...l-tertiary butyl 2,6dibr0mophenyl acetate. 4 1 5. 45 37. 0 19. 2 D-4-nony1 2,6-dibromophenyl acetate 9 1 6. 6 96. 0 95. 8 E Tribromophenylstearate 0 17 6. 0 100.0 100. 0 11- Pentabrornophenyl stearate 0 17 5. 196.0 96.0 G Pentabromophenyl 0leate 0 17 4.8 99.0 91.0

It is to be noted thatthe total number of carbon atoms in R and R of theflame retardant compound used in preparing fibers A through C is 9 orless and that the retention of the compounds by the fibers both afterspinning and after dyeing is substantially less than the retention ofthe compounds by the fibers D through G. R of the flame retardantcompound used in preparing fibers D through G contains more than 9carbon atoms.

EXAMPLE IV Example I is repeated except about 8.4 parts of 4- nonyl,2,6-dibromophenyl acetate and about 0.6 part of antimony trioxide aremixed with the 1000 parts spinning solution. The resulting fiber isself-extinguishing.

EXAMPLE V Example I is repeated except a solution of about 2 parts oftrioctylphosphate and about 7 parts of 4-nonyl 2,6-d1- I bromophenylacetate is dispersed in the spinning solution instead of the flameretardant of Example I. The fiber is self-extinguishing.

EXAMPLE VI Example I is repeated except about 7 parts of di(4-octanoyltetrabromophenyl) propane are substituted for the 4-nonyl,2,6-dibromo-phenyl acetate. About 100 percent of thedi(4-octanoyltetrabromophenyl) propane is retained by the filament afterspinning and about 99 percent thereof remains in the fiber after drying.

EXAMPLE VII An intimate mixture is prepared containing about 50 partsdi(4-bromopropoxy-2,3,5,6 tetrabromophenyl) propane, about 4 partsantimony oxide, about 22.5 parts of the copolymer of Example I, about 82parts sodium thiocyanate and about 95.5 parts water. About 50 parts ofthe resulting mixture are substituted for the 4-nonyl, 2,6-dibromophenyl sebacate in the 1000 parts spinning solution of Example Iand a fiber is prepared by the process of Example I. The fiber thusobtained contains about 2.6

pared from a saline solution of polymer and having improved flameresistance containing an amount suflicient to impart flame resistance ofa halogenated aromatic comwherein R is hydrogen, chlorine, bromine or analkyl radical having from 1 to 9 carbon atoms; R is a alkyl radicalhaving 1 to 22 carbon atoms and the sum of the carbon atoms of R and Ris greater than 9; R is methylene, isopropylidene, oxygen or sulfur; Ris an alkyl radical containing at least one carbon atom; R is a 2,3-dibromopropyl group; X is bromine or chlorine; m is an inter of from 0to 22 and n is an integer of from 0 to 4 with the proviso that eachformula contains at least two aromatically bound halogen atoms.

2. The product of claim 1 wherein the halogenated aromatic compound is4-nonyl-2,6-dibromophenyl acetate.

3. The product of claim 1 wherein said polymer contains from about 1percent to about 20 percent of said halogenated aromatic compound.

4. The product of claim 1 wherein said halogenated aromatic compound isdi(4-octanoyl dibromophenyl propane, di(2,4,6-tribromophenyl) sebacate,pentabromophenyl oleate, tribromophenyl stearate, pentabromophenylstearate or nonyldibromophenyl sebacate.

5. In the process for preparing the solid shaped acrylonitrile polymerproduct of claim 1 wherein the acrylonitrile polymer dissolved in salinesolution is mixed with a flame-resisting agent and spun into a shapedarticle, the improvement which comprises using as the flame-resistingagent an effective amount of a halogenated aromatic compound having amelting point below about 100 C. and having the formula wherein R ishydrogen, chlorine, bromine or an alkyl radical having from 1 to 9carbon atoms; R is an alkyl radical having 1 to 22 carbon atoms and thesum of the carbon atoms of R and R is greater than 9; R is methylene,isopropylidene, oxygen or sulfur; R is an alkyl radical containing atleast one carbon atom; R is a 2,3- dibromopropyl group; X is bromine orchlorine; m is an integer of from 0 to 22 and n is an integer of from 0to 4 with the proviso that each formula contains at least twoaromatically bound halogen atoms.

6. The process of claim 5 wherein from about 1 percent to about 20percent of said halogenated aromatic compound is mixed with saidspinning solution.

7. The process of claim 5 wherein said spinning solution is an aqueoussaline solution of an acrylonitrile polymer.

8. An acrylonitrile fiber prepared by spinning the composition of claim1.

References Cited UNITED STATES PATENTS 2,984,694 5/1961 Gleim 26045.953,075,944 1/ 1963 Wick et al. 2604595 3,210,315 10/1965 Blackburn et al.26045.'85 3,275,596 9/1966 Klug et al. 2604595 3,310,525 '3/1967 Lappinet al. 26045.95

HAROLD D. ANDERSON, Primary Examiner US. Cl. X.R.

26029.6 AN, 45.95; 264182 Dig 84 UNITED STATES PATENT oTFTcE EERTEFICA lPatent Non 3, ,551" Dated May 2, 1972 Inventor(s) Richard FrederickSchmidt 80 Joseph Jacinto Pellon It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown belcw:

Col. 2, line 9, "resistance" should read resistant Col. 5, line 2,"halogenated compound" should read halogenated aromatic compound C01. 6,Claim 1, formula No. 2, right top side:

OR should read 0R Col. 7, Claim 5, Formula No, 3, On the left side:

m should read R gO- Signed and sealed this 19th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents USCOMM-DC 60376-P89 w 0.5. covzmmzm' PRINTING orllc: mmo-auu-am F ORM PC1-1050 (10-69)

